This invention is concerned with novel ocular inserts, with or without a pharmacologically active agent, comprising low molecular weight polymers including polyvinyl alcohol which do not cause blurred vision to the same extent as hydroxy propylcellulose of high molecular weight and which when formulated with enteric coating materials as a constituent of the matrix provides a means for controlling and predicting dissolution rates for slow release and prolonged residence times.
Solid ocular inserts are now well known in the art and they are generally a great advance over the prior liquid and ointment forms of medication. However, the prior art solid biosoluble ocular inserts frequently caused blurred vision because the high molecular weight polymers commonly employed altered the viscosity and refractive index of the tear film. These changes resulted in the formation of "Schlieren" or discontinuities in the precorneal tear film. The prior art solid biosoluble inserts also served to augment the blurring by the presence of a large volume of the gelatinized, hydrated polymers which tended to fracture into fragments due to blinking, giving rise to a potentially more rapid dissolution.
Now with the present invention there is provided ocular inserts that minimize the blurred vision effect by providing materials that do not materially change the viscosity and index of refraction of the tear film and optionally provide those materials at a rate sufficiently slowly as to provide only low volumes of the solubilized polymers. In addition, the compositions described do not form gelatinous masses in the cul-de-sac.